1. Field of the Invention
The invention relates to a pixel structure and a fabrication method thereof, and particularly, to a pixel structure having an etching stop pattern and a fabrication method of the pixel structure.
2. Description of Related Art
Nowadays, a multimedia technology has been well developed, which mostly benefits from the development of semiconductor devices and display apparatuses. As for displays, LCDs with advantages such as high definition, favorable space utilization, low power consumption and radiation-free operation have gradually become the mainstream of the market. In general, the thin film transistor liquid crystal display (TFT-LCD) is mainly assembled by a thin film transistor array substrate, a color filter substrate, and a liquid crystal (LC) layer sandwiched between the two substrates.
A known thin film transistor array includes scan lines, data lines, and pixel structures. In specific, the pixel structure includes a thin film transistor and a pixel electrode, wherein the thin film transistor electrically connects the pixel electrode to the corresponding scan line and the corresponding data line. The thin film transistor generally includes a gate connected to the scan line, the semiconductor layer located above the gate, the source and the drain located on the semiconductor layer, wherein the source is connected to the data line.
The film layers (including a metal layer, a semiconductor material layer, an insulation layer, etc.) deposited on the substrate are required to be patterned to form the needed component during fabricating the pixel structure. A known pixel structure is substantially consisted of a first metal layer, a first insulation layer, a semiconductor layer, a second metal layer, a second insulation layer, and a pixel electrode layer, wherein the first metal layer includes the scan line and the gate, and the second metal layer includes the data line, the source, and the drain. The five film layers besides the first insulation layer are respectively patterned so that a five mask process is provided for fabricating the known pixel structure.
In the five mask process, the semiconductor layer can be etched during etching the second metal layer. Accordingly, a method of forming an etching stop pattern on the semiconductor layer for protecting the semiconductor layer and serving the etching stop effect is provided. Thus, the fabrication of the pixel structure becomes a six mask process from the five mask process. The six mask process has the issue of high cost owing to an additional mask and further has the issue of the mis-alignment between the semiconductor layer and the etching stop pattern.